SAJSET-01-2023-0011 Evaluation of some geotechnical properties of clay stabilized with piliostigma thonningii pod ash for road filling

Abstract

Construction of engineering structures on problematic soils such as clay is difficult and expensive, it sometimes requires hauling of good materials from other sources or the stabilization of in-situ soil to reduce cost. The aim of this paper is to evaluate some geotechnical characteristics of clay soil stabilized with Piliostigma Thonningi Pod Ash (PA] for road construction. The Piliostigma Thonningii used in this study was obtained from Gwaraje Village, Katsina state Nigeria. The pod was burned in the furnace under a controlled temperature to obtain pod ash (PTA). The percentages of PTA used were 2%, 4%, 6%, 8% and 10%, then Compaction, Atterberg limits, California bearing ratio (CBR) and direct shear tests were conducted on control clay (0% PTA) and PTA stabilized clay. The compaction test result shows an increase in maximum dry density with the increase of PTA percentage, while optimum moisture content remains constant at 4%, 6% and 8% PTA stabilized samples. Generally, CBR, shear strength and bearing capacity were improved with the increment of PTA percentage, the optimum improvement was obtained at 8% PTA stabilized samples. Liquid and plastic limits of the stabilized clay were increased which shows an improved clay strength under moisture, therefore 8% of PTA is the optimum content in stabilizing clay that could be used for effective road fillings.